Current knowledge of the metabolism of zinc is summarized in relation to the clinical and public health importance of human zinc deficiency. Zinc metabolism is considered in relation to estimations of zinc requirements. Special attention is focused on the role and limitations of regulation of intestinal absorption of exogenous dietary zinc and of intestinal excretion of endogenous zinc in the maintenance of zinc homeostasis. The dynamic interrelationships between these variables and between each of these and readily exchangeable pools of body zinc are highlighted, as is the impact of dietary phytate on zinc requirements. Measurements of these variables utilizing zinc stable isotope techniques can provide quantitative information on zinc homeostasis and dietary zinc requirements in different communities, as well as facilitating assessment of alternative strategies for preventing zinc deficiency.
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